The present invention relates to a welding-, cutting-, or heating torch with a torch head provided with an outlet nozzle or outlet nozzles and a torch body connecting the torch head with a torch housing and provided with feed passages therethrough, whereby at least part of the torch body and the torch head is flown through by a cooling medium for convective heat transmission.
The modern use of such torches and especially welding torches for hand or machine operation leads to increased temperatures in the region of the torch head nozzles. This is especially the case during so-called protective gas welding, since the thermal loading of the torch head increases during use of protective gases, especially by use of noble gases, such as argon or helium. Since in the modern welding technique high alloyed steels, as well as light metals are often welded according to the protective gas welding process and especially according to the Sigma, respectively MIG-MAG-process, the use of pure noble gases as protective gas is absolutely necessary, since these noble gases best prevent the influence of the atmosphere onto the welding- and welding-boundary zones of alloyed steels and light metals. However, also at other welding processes, for instance at the WIG welding process, the plasma-welding and cutting process, the beneath-powder-welding-and heating torches which operate with a burner gas-oxygen mixture, the thermal loading of the torch head continuously increases.
In known torches of the above-mentioned kind, it has been tried to cool the torch head, and especially the thermally highly loaded nozzle zone thereof, exclusively by cooling media under use of convective heat transmission. In practice it has however been shown, that such a cooling by means of convective heat transmission is either not sufficient to prevent a thermal overloading of the burner head, or that for such cooling such a technical expenditure is necessary which is unacceptable for a practical operation. All cooling systems operating exclusively with convective heat transmission require a high technical expenditure since circulation pumps for the cooling medium are necessary while the connecting conduits complicate the torch operation and may lead to accidents. The known cooling systems operating strictly with convective heat transmission have the basic disadvantage that only a relatively small temperature drop is possible at a heat transport over longer distances or that considerable large amounts of cooling media with a high flow speed are necessary.